the word 'taxi' is a shortened form of 'taximeter cab', where 'taximeter' refers to the fare-calculating device. 'Taximeter' itself entered english from french, derived from the german 'taxameter', a compound of the medieval latin 'taxa' (meaning 'charge' or 'tax') and the suffix '-meter' (meaning 'measure'). the core idea of a measured charge is preserved in the modern meaning. the verb sense, describing an aircraft's ground movement, emerged by analogy with a car moving under its own power to a designated point.

this word is a loanword and a clipping, not productively formed from separable morphemes in english.